ML20197A728
| ML20197A728 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 02/19/1998 |
| From: | Joseph Holonich NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Bill Dean NRC (Affiliation Not Assigned) |
| References | |
| NUDOCS 9803090362 | |
| Download: ML20197A728 (37) | |
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.] NUCLEAR REGULATORY COMMISSION WASHir4GToN, D.C. 206N@001 N * * * * * /g February 19, 1999 MEMOFMNDUM TO: William Dean, Director Project Directorate ll 1 Division of Reactor Projects l/il Office of Nuclear Reactor Regulation FROM: Joseph J. Holonich, Chief, MW '"
Uranium Recovery Branch Division of Waste Management Office of Nuclear Material Safety and Safeguards
SUBJECT:
ACTION ON DAM SAFETY INSPECTION AT THE VIRGIL C. SUMMER l
NUCLEAR POWER STATION SERVICE WATER POND DAMS, DOCKET NO. 50 395 The final inspection report from the Nuclear Regulatory Commission's technical assistance contractor, the Federal Energy Regulatory Commission (FERC), was received and has been evaluated. The inspection was conducted on February 27,1997.
Attached is a draft letter for use in transmitting the FERC report to the licensee, and three original t,oples of the FERC inspection report, dated September 24,1997, containing color photographs for the licensee's records. With respect to the three copies of the FERC report, we expect that one copy will be transmitted to the licensee, one copy to Central Files, and one copy to Office of Nuclear Reactor Regulation (NRR) Projer:ts. We will transmit an original copy to Region ll, along with a copy of this letter. It is suggested that other necessary copies for the NRR procedure requirements can be made by normal black and white copy machine, including only Xerox type copies of the photographs.
The conclusion of the inspection was that there were no conditions observed that would impair the immediate safety and permanence of the developed works. A list of seven recommendations will be found on page 11 of the FERC report. All seven recommendations should be followed by the licensee. In addition, FERC concluded that the dam should be categorized as a low hazard dam, thus verifying the previous NRC conclusion.
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i W. Dean As noted in the report, licensee representatives and their design consultant accompanied the Office of Nuclear Material Safety and Safeguards personnel, along with an FERC representative during this audit. The attendees participated in relevant discussions while at the site. An independent NRO Inspection Report was not generated as a result of this activity.
Docket No. 50-395 Attachments: As stated cc w/ Attachments:
MPadovan, NRR GBagch!, NRR BBonsor, Ril DISTRIBUTION: FILE CENTER PUBLIC NMSS r/f URB r/f CNWRA ACNW CCain w/o Encl.: MFederline CAbrams MLayton DOCUMENT NAME: S:\DWM\ URB \ SUMMER.MEM OFC URB _ URB i NACE DRom/bh JHolonich lDATE ot/'%98 / /98 OFFICIAL RECORD COPY 4
W. Dean 2- February 19, 1998 As noted in the report, licensee representatives and their design consultant accompanied the Office of Nuclear Material Safety and Safeguards personnel, along with an FERC representative during this audit. The attendees participated in relevant discussions while at the site. An independent NRC Inspection Report was not generated as a result of this activity.
Docket No. 50-395 Attachments: As stated -
cc w/ Attachments:
MPadovan, NRR GBagchi, NRR BBonsor, Ril l DISTRIBUTION: FILE CENTER PUBLIC NMSS r/f URB r/f CNWRA l ACNW CCain w/o Encl.: MFederline CAbrams MLayton DOCUMENT NAME: S:\DWM\ URB \ SUMMER.MEM *See previous concurrence OFC @ 8 @
NAME hk JHobch DATE- 2/13/98 2/4/98 l
\- OFFICIAL RECORD COPY
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4 W. Dean As noted in the report, licensee representatives and their design consultant accompanied the Office of Nuclear Material Safety and Safeguards personnel, along with an FERC representative during this audit. The attendees participated in relevant discussions while at the site.- An independent NRC Inspection Report was not generated as a result of this activity. -
Docket No. 50 395 Attachments: As stated cc w/ Attachments:
BBonaer, Ril l
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DRAFT LTR TO LICENSEE:
Mr. Gary J. Taylor Vice President, Nuclear Operations South Carolina Electric and Gas Company Virgil C. Summer Nuclear Station Post Office Box 88 Jenkinsville, South Carolina 20065
Dear Mr. Taylor:
SUBJECT:
RESULTS OF DAM SAFETY INSPECTION RELATED TO THE CATEGORY l SERVICE WATER POND DAMS AT THE VIRGIL C. SUMMER NUCLEAR STATION On February 27,1997, an inspection was conducted at the Virgil C. Summer Nuclear Station for the Category I Service Water Pond Dams. The U.S. Nuclear Regulatory Commission staff has received and evaluated the final report from its technical assistance contractor, the Federal Energy Regulatory Commission (FERC), related to this inspection. Included in the FERC report (page 11) is a list of the actions that should be taken by you to insure the continued safety of the cams of the Category I service water pond consistent with the Federal Guidelines for Dam Safety (1979) and the Dam Safety Program Act defined in the Water Resources Act of 1996. It l is requested that you provide a written response to these actions within 180 days of receipt of l this letter, except as otherwise noted. It should be noted that since the NRC staff requested l actions are based on the information contained in the FERC report, no additional response to l
findings and followup actions contained in the FERC report is required.
The conclusion of the inspection was that there were no conditions observed that could be considered an immediate threat to the safety of the dams or nuclear facility. However, there were seven items maintenance identified to enhance inspection and operation. The action items generally relate to regrading for enhanced performance, and monitoring improvements.
As previously mentioned, an original copy of the FERC report, dated September 24,1997, which contains color photographs taken of various areas that were inspected during the audit, has been provided as an Enclosure.
If you have any questions regarding the responses and information requested, the report, or schedule for submittal of information, please contact me at (301) 415-1423.
Sincerely, Mark Padovan Project Manager Project Directorate 111 Division of Reactor Projects - t/11 Office of Nuclear Reactor Regulation Docket No. 50-395 - - --
Enclosure:
FERC/NRC Operation Inspection Rpt Attachment
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Operation Inspection Report for Nuclear Regulatory Commission Inspected by FERC Atlanta Regional Office 4
Date of Inspection February 27. 1997 4
Dam (name) Service Water Pond Dame (North Dam. South Dam. East dam, and West embankment)
Location V. C. Summer Nuclear Station ,Fairfield South Carolina (River or reservoir) (State) i NRC Licensed Project V. C. Summer Nuclear Station Features of Dam and Impoundment Inspected Dams, oumo house, and embankment
. Inspected by Wayne B. Kina l Accompanied by Ms. Kristina Massev and Mr. Robert Whorton, i
emolovees of the licenseer Mr. Arthur Dvinoff. Embankment Desianer from Geosystems; consultantsi and Mr. Dan Rom. Nuclear Reaulatorv Commission.
Weather Part1v cloudv. temoeratures in the hich 60's P
Summary The inspection covers an impoundment within the Monticello reservoir of the Fairfield pumped r torage hydropower development.
The inspection included three dams, one embankment, intake pump house, and features around the service water impoundment.
No conditions were observed at the time of the inspection that could be considered an immediate threat to the safety of the dams or nuclear facility. Several improvements in maintenance, Attachment
monitoring, inspection and drainage were discussed in the exit meeting and are described in the report.
submitted Wayne B. King, P.E.
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Proiect Descriotion The V. C. Summer Nuclear Station service water pond (SWP) ,
was constructed to provide emergency cooling water for the plant reactor. The site is located on the southern rim of the 6,800-acre Monticello pump storage reservoir (FERC Project 1894),
which is the normal source of reactor cooling water. The site is epproximately 30 miles north of Columbia, South Carolina.
Three dams and the west embankment form a 44-acre sut joundment of the Monticello reservoir (See Figure 1). The three dams are homogeneous claycy silt and silty clay earth structures with 3-foot horizontal to 1-foot vertical (3H:1V) slopes on the service water pond side and 3.5H:1V on the Monticello reservoir side (see Figures 2, 3, and 4). The west embankment also has 3H:1V slope on the SWP side but has a 1H:1V slope which abuts the general fill of the nuclear reactor site.
All slopes are armored with riprap to the toe on the Monticello side of the embankment. The slopes on the SWP side of the dams and west embankment are armored to the toe or elevation 415.0 NGVD whichever is higher.
The dams were designed for a factor of safety of 1.1 during earthquake and 1.2 for rapid drawdown. The three dams also include internal and/or toe drainage features and are founded on dense decomposed rock and or dense sapprolite. A grout curtain was also placed along the centerline of the North dam from station 4+00 to 16+75. A complete description of dam construction, materials, testing, design, and geology can be found in the licensee's Final Safety Analysis Report (PSAR)
Section 2. 5. 6 " Embankments and Dams."
The Monticello reservoir is used for pump storage operations which causes daily fluctuations between its reservoir and the SWP of up to 5 feet. The service water pond is hydraulically connected to the Monticello reservo4r by a 36-inch-diameter pipe that runs Jrom the main circulating water intake structure, along the west embankment to the service water intake structure (pump house) at elevation 415. Should the main reservoir be drained, approximately a 1,200-acre-foot pond (at elevation 415 feet) would be retained for safe shutdown and emergency cooling for 30 days as required by the Nuclear Regulatory Commission (NRC).
Table 1 Pertinent Data Sheet Resen' air Normal water surface elevation 425.0 feet NGVD Surface area 6i) 423.011 NGVD 44 acres Volume @ 425.0 f1 NOVD 1,600 acre feet Minimum water surface elevation 415 feet NGVD Surface area (Fi 415 feet NVGD 36 acre feet Volume GD 415 feet NGVD 1,200 acre feet llazard potential Low North dam:
Crest elevation 438.0 feet NOVD Crest width 30.0 Crest length 1.500.0 Ileight (maximum) 129 Volume 785,000 cy NATDAM ID Number South dam:
Crest elevation 438.0 feet NGVD Crest width 30.0 feet Crest length 765 feet licight (maximum) 98.0 feet Volume 273.000 cy NATDAM ID Number '
East dam:
Crest elevation 438.0 NGVD Crest width 40.0 Crest length 1.150
Volume 44.000 cy NATDAM ID Number West embankment:
Crest elevation 435.0 ft NGVD Crest width 50.0 feet I Crest length 1.900 feet Volume 1.169.000 cy NATDAM ID Number Maximum Storm Surge:
Monticello (80 mph winds) 12.5 feet (PMP + mph winds) 11.6 feet Service pond (80 mph winds) 4.5 feet (PMP + 8 mph winds) 8.6 feet A. Safety of the Proiect.
- 1. Dams, Dikes, and_Apauptenant Stntetures. No physical conditions were observed that could be considered an indication of deficiencies in dam safety or a safety threat to the public. Several items regarding maintenance, inspection, and monitoring of the project need improvement to properly observe and document the condition of the dams and are discussed throughout the text and listed in the last paragraph of the report.
Vehicle access is provided along the crest of the dams except for the southern one-half of the north dam which is blocked for security reasons. All portions of the project were accessed by walking; however, only the portions of the dams and west embankment that were above the SWP and the Monticello reservoir elevations were access; ole for observation. Portions of the west embankment and pump house were in high security zones where no cameras were allowed,
- a. North Dam. The north dam (see Figures 1 and 2)
is the largest of the four structures built to contain the
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emergency supply of cooling water. No deficiencies in alignment, settlement, or slope stability were noted during the inspection.
The crest and slopes appeared normal on both the SWP side and the Monticello side of the dam (photograph 1). The Monticello side of the north dam could be severely impacted by wave run-up and therefore is armored with large riprap (Photograph 2). The abutments of the north dam appeared normal as no signs of distress were observed (Photographs 3 and 4). Heightened security awareness has caused the licensee to install a vehicle barrier on the crest of the north dam (Photograph M
- b. East Dam. The east dam (Figures 1 and 3) appeared in good condition. No deficiencies in alignment or slope stability were noted. Riprap on both slopes appeared normal with no beaching, settlement, or other indications of displacement (Photographs 6, 7, 9, and 9). Abutments appeared normal except for an erosion rill at the toe of the dam near the south end on the Monticello side (Photograph 10). The licensee had recently regraded the natural formations to direct surface runoff away from the dam but more improvement was needed in this one area.
- c. South dam. No indications of displacement, sloughing, or slides were observed in the crec., slopes or abutments of the south dam (Photographs 11 through 14). While there were no visible indications of deficiencies above the elevation of the Monticello reservoir, the condition of the dam slope and the discharge canal underwater are unknown. A drop
weight lead line or depth survey of these areas was requested during the exit meeting to verify that no erosion within the discharge canal or along the adjacent slope of the dams had occurred. Riprap appeared normal without signs of beaching or degradation. The first layer of bedding stone for the riprap was exposed to allow examination (Photograph 15). The material appeared as that specified in the design (reference FSAR Figure 2.5 - 147).
- d. West Embankment. The west embankment (Figures 1 and 4) is similar in construction and materials and configuration except for the landside slope which was constructed at 1H:1V with adjacent fill for the reactor site and support buildings.
No cracks, areas of settlement, or slope deficiencies were observed along the embankment (Photographs 16 and 17). Abutments also appeared normal. Riprap appeared normal as would be expected with the small impoundment and short fetch. Surface runoff along the SWP side of the security fence (Photograph 18) is ponding at the top of the embankment causing softening of the soil surface along the fence. The swale should be filled to prevent ponding and allow surface runoff to flow into the SWP.
- e. Rumo House. The pump house is located within the perimeter of the security fence whereas no cameras are allowed. The pump house was inspected on each level. The cracks in the structure concrete are small but monitored by the site engineering team and documented in site records. Licensee employees stated that the cracks were associated with settlement that occurred shortly after or during construction. No major
cracks, chifting, or misalignment of structural members was obscrued. A corrugated metal pipe (CMP) is used to discharge water back into the pond (Photograph 19). This CMP is highly corroded above the 9ond level. The condition of the pipe and ps9sfble erosion of the embankment slope was discussed with the licensco ' n rep;osen::.atives and the NRC. A lead-line survey along the CMP alignment is to datermine slope con'itions underwater.
- 2. InAtIngentation. The three dams and enbankment are monitored for vertical and horizontal movement on a schedule approved by the NRC. Sixteen monuments are located in the north dam, 11 along the south dam, and 11 along the west ert.bankment.
The service water pump house has four monuments, and three masto are located on the service water pump house intake tunnel tc measure settlement. Four ranges, perpendicular to-the alignment t
of the west embankment slope, are surveyed using a drop weight.
The data which is collected at a 5-year interval and last collected in 1995, shows basically no ground movement. There is variability in the survey data along the ranges that measure the riprap slope of the west embankment. The smaller deviations in the survey data from the original design elevationa can be partially attributed to surveying in riprap and poor field surveying technique. This accounts for the plus or minus 2-foot range in certain points. The large offset (+13 feet) from the slope dee<3n is apparently due to elevation of the natural ground in the bottom of the SWP which was not accounted for in the organization of the survey program. The presentation of the slope survey data should be annotated to explain the regular
-deviations and the large offsets that occur toward the end of the range lines that start from monuments WE-12, WE-23.
Twelve piezometers were installed in the north dam, and six piezometers were installed around the service water pump house.
Nine of the twelve north dam piezometers are inundated by the SWP and Monticello reservoir. Monitoring of the dam crest piezomoters ceased when the phreatic levels stabilized near the reserveir/SWP elevations. The west embankment piezometers were no longer read after the ground-water level in the plant area and west embankment stabilized.
The FSAR Section 2, 5.6 " Embankment and Dams" paragraph 2.5.6.8.2 (pg 2, 5 - 135) describes the need for monitoring the piezometers near the toe of the dams of the Monticello side in
-the event of loss of the Monticello reservoir. Since these piezometers are inundated under normal operating conditions and will only be monitored should the Monticello reservoir be drained, the FSAR should be edited to include cleaning, testing, and evaluation of the inundated piezometers when they become accessible.
The crest piezometers have not been read since the phreatic line in the dams have stabilized _according to the FSAR. These piezometers are easily accessed and should be cleaned, tested, and evaluated for future use. Routine maintenance and evaluation procedures of the piezometers should also be included in the FSAR.
Crack surveys and diagrams are also obtained for the structural concrete in the pump house and in the intake tunnel.
l The pump house cracks appear to be associated with settlement i during or after construction. The pump house cracks appear stable'according to notes and licensee employees. Cracks in the intake tunnel greater 'han O'.015 inch-were grouted in 1978 prior to filling the SWP. NRC license conditions were modified to require an inspection of the tunnel at least every 5 years. The last inspection and crack survey completed in 1993 identified several new cracks. Thirteen cracks identified as wider than 0.015 inch were grouted in January 1994. Crack diagrams are documented in the licensee's calculation records.
- 3. Hazard Potential Classification. The failure of any of the SWP dams will allow flow into the Monticello reservoir only to the extent of the difference in water elevation between the Monticello reservoir and the service water pond. The traditional hazard classification would be " Low" since no inhabited structures or areas normally occupied exist downstream oof the SWP.
- 4. Consultant's Safety Insoection Reports. Part 12 regula-tions do not apply to this project as it is regulated by the NRC. The last inspection conducted in accordance with NRC Regulatory Guide 1-127 was completed by the licensee on October 20, 1995. Erosion-of natural soil formations and some emergence
-of brush and trees were-noted. No visual deficiencies or indications of deficiencies from monitoring data were noted during that-inspection period. The next scheduled inspection required by the NRC is in the year 2000 (5-year interval).
- 5. Licensee's Insoection Proaram. From discussions
with the licensee's personnel, no routine inspections other than the 5-year inspection are conducted. Discussions between FERC, NRC, and the licensee's representatives concluded that-an annual inspection with an appropriate level of documentation should be implemented immediately.
B. Operation and'Maintenaaqa.
- 1. Egas, Dikes. and Anourtenant Structures. The SWP dams and embankments appear to be properly maintained and operated. Abutments were recently regraded to direct surface runoff away from the dams. The one area still needing some improvement is on the Monticello side of the south leg of the east dam. Some brush and small trees growing in the dam and abutments should be removed.
2.- Egillway Gates and Standby Power. The project has no spillway gates and therefore standby power for emergency gate operations is not required.
- 3. Power Plants. There is no hydro generating plant at this project.
- 4. Reservoir. The SWP is small (44 acres maximum) .
Some. slight erosion is evident in the natural soil formations on the-pond side. Moderate erosion exists in the abutment along '.he Monticello side of the south leg of the east dam and regrading should be' conducted to direct surface runoff away from the toe.
- 5. Recor_ds. Instrumentation data construction and design documents are maintained at the sites per NRC requirements._ Dam and embankment investigation and design data can be found in licensee's document " Final Safety Analysis
Report, Section 2.5.6. Embankments and Dams." Instrumentation l data and records, monitoring guidance, and inspection documentation can be found in various records. Documenta-tion appears adequate with the exception of annual inspections.
- 6. Emergency __ Action Plan. Under hydraulic hazards, the dam would be classified as a " Low" hazard structure so no emergency plan is required. Any series of events that result in threats to the safety of the nuclear plant would be processed through the nuclear plant warning system evacuations.
C. Environsitatcal, Public Use, and Saf312 The SWP pond is closed to the public. Earthen dams, embankment, or natural formations form the perimeter of the pond so no boat access from the main reservoir is possible. No additional actions to protect life and property appear to be required.
- 1. Egblic Safety Plan. Not applicable.
- 2. Need for Action. None.
- 3. EnvironatD111 and Public Use IDAppction. No environmental or public use or public safety problems were noted.
The dams and the SWP are closed to the public. No additional actions are needed to protect life and property.
D. Matters of_ Commission _ Interest.
- 1. Additions, Betterments, Lgggps, Retirements, or Needed_txtensions. None.
- 2. Ryouirina Commission Action. Not applicable.
- 3. Proiect Compliance. Not anplicable.
E. Findings and Followuo Actions. The inspection revealed no conditions that might adversely affect the immediate safety of
the project. Several inspection and maintenance improvements were discussed with the licensee and NRC in tua exit meeting of February 27, 1997. These items also discussed in the text of this report and are summarized below:
- 1. Remove small brush and trees in the embankment and ,
abutment.
- 2. Test and evaluate accessible embankment dam piezometers.
- 3. Inspect the dams and west embankmant annually.
Document conditions and maintain records of the inspections. A checklist and brief narrative is suggested.
- 4. Regrade the abutment of the east dam to direct surface drainage away from the toe of the dam.
- 5. Regrade the area along the fence east of the SWP pump house to allow sur.* ace runoff to drain from the top of the embankment.
- 6. Conduct lead-line surveys on the discharge channel sida of the south dam and aast 6am and the discharge channel to ensure that no erosion has occurred within the dams or channel bottom which might affect dam stability.
- 7. Conduct a lead-line survey along the alignment of the SWP pump horce oischarge pipe. This CMP is highly corroded and the survey is to ensure leakage has not eroded embankment materials. Repair or replace the CMP as necessary.
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0 Photograph 102/27/97 North dam crest and service water pond slope.
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i Photograph 202/27/97 1
North-dam Monticello side slope at east abutment.
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Photograph 302/27/97 North dam (background) abutment with west embankment (foreground).
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e Photograph 402/27/97 West embankment from abutment with north dam to pump house, n _ - _ _
Photograph 502/27/97 Vehicle security barrier on north dam, i
e Photograph 602/27/97 East dam north leg, Monticello side.
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Photograph 702/27/97 North leg of the east dam, SWP side.
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Photograph 802/27/97 Crest of the north leg of the east dam, t
e Photograph 902/27/97 South leg of the east dam, Swp side.
l Photograph 1002/27/97 South leg of the east dam, Monticello side. Note erosion at toe.
Photograph 11 02/27/97 South dam and abutment on the discharge channel side, m
Photograph 1202/27/97 South dam abutment on the SWp side.
Photograph 1302/27/97 South dam crest from west abutment.
Photograph 1402/27/97 South dam SWP side near east abutment.
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Photograph 1502/27/97 Riprap and bedding stone, SWP side of south dam.
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I Photograph 16 02/27/97 West embankment southeast end.
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Photograph 1702/27/97 West embankment crest.
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Photograph 1802/27/97 West embankment security fence east of pump house.
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Photograph 1902/27/97 Service water pump house, cc: D2SI, Dep. Dir.
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